It's pouring down. We're sheltering in a food and drink concession in the shadow of the Orbit. The canvas roof is pounding with rain that puddles at our feet.
Tricky climate then for Andrew Altman to paint a picture of what's to come. Still, he gives it a go.
The chief executive of the London Legacy Development Corporation (a "government in exile") says: "You can imagine people will be able to sit out on the lawn, look at the Orbit, look at the stadium.
"There's going to be a permanent cafe, shop, a restaurant, you'll be able to sit out on the roof but in a public space. You think about the Serpentine gallery - we should want that in east London.
"In these landscaped rooms that we're going to create, each one is going to be very different - some will have an amphitheatre where there will be small concerts, some will be a kids' play area, one will be a splash pool. We want it to be fun for families."
But that's looking ahead to Easter 2014 when the retro-fitting has been complete, the temporary Olympic venues removed, the park transformed and transferred.
What he's keen to share with us is this: He and his team have taken a decision to set a tough deadline of a year after Games, July 2013, to begin re-opening the park in phases, North Park first.
He says: "Our programme is to get it open as quickly as we can, get it open from North to South, get it open from a year after the Games, from July 2013 till Easter 2014, phased re-opening, get people in the park so they can enjoy it.
"The easy decision would be to say you'll open the park in 2014, give yourself a lot of time, reopen the whole thing, when you've worked everything out but that's not really right.
"People are anxious to get on the park. We want to keep that memory, that excitement alive."
He doesn't want the park to slip from people's minds, become a thing over there to which they're not invited.
"You're not going to have the density of people to use the park right away, to make it active and feel alive. So we're going to have to do a lot to get people in here and feel like it's their park."
London Assembly member John Biggs agrees with the concern, if not the length of the entire project.
He said: "I understand they've got to take down a few bridges and structures but there's a risk the Olympic buzz will have faded away in two years' time. These engineers serve us and people should have a chance to enjoy the park. If the Olympics are to have a legacy, people need access to the park."
If Andrew Altman worries about anything, it is this. He said: "The first years of the park are key. If it's just a passive park, fine, it's nice, but it won't work.
"We've got to get people into this park. Truthfully, it's going to be through giving people stuff to do.
"We'll open up the North Park a year after Games, have people come out, have London's greatest picnic which will happen over that summer.
"The North Park is like a river valley. Quiet, beautifully landscaped, a place where people can sit out, have a picnic, kick a ball about."
If it's not raining.
